Spark plugs are responsible for transferring energy from the ignition system into the combustion chamber.  The spark plugs also transfer heat into the cylinder head where it is pulled away via the exhaust stroke. Why do you think those exhaust pipes are so hot?  Plugs come in different heat range settings. Which is best for you, well 9 times out of 10 the heat range plug your service manual is telling you to use will be right. Now if you are loading up a full dressed motorcycle and are going to be doing some real hard touring in high temps you might want to consider using a colder running plug vise versa for the opposite situation.

In order to change your plugs you’ll need to determine what size hex your plugs are and then grab the correct socket to match so you can remove the plugs. Remove the plug wires form the spark plug and go ahead with your wrench or ratchet and break the spark plug loose. Once you loosen the plug enough you can grab it with your hand and remove it.  Careful if your engine is still hot, you’ll burn your hand. Wait until your engine has cooled some to change the plugs.  If the plugs are totally black and reek of fuel then it’s telling you the engine is running rich, this means it’s getting too much fuel during the process of mixing fuel with air. A black plug could also mean your air filter is clogged or maybe you made some changes to your ride, like a set of pipes which is effecting how fast the exhaust is being pulled away, or it could be as simple as a change in altitude and air. A rich plug means that you will lose power as the plug tip temperature drops and causes the plug to foul out. The engine is running too fat (rich) and this is why you’ll see a plug covered with carbon or unburned fuel creating that black look.

If the plugs are totally white then the engine is telling you it’s not getting enough fuel, it’s running lean.  A lean mix means the cylinder and plug tip temperature are running high. This bleached look will indicate a lean fuel air mix. Sparkplugs should have a beige color to them; if they look real black or white and you can’t pin-point why then you’ll want to have a certified mechanic take a look. Your spark plugs should also be even in color. You never want to see one spark plug black and one beige; both spark plugs should have the same color. A fuel mixture problem could be robbing you of power. Your Engine mixes fuel with air and combustion happens when the air fuel mixture meets the spark from the spark plug. The faster you get air and fuel in and the quicker you get the exhaust out will enhance the performance of your ride.   When changing sparkplugs you’ll need to gap the electrode according to the spec listed in your Service manual. Use a spark plug gapping tool to get the correct gap.  The “gap” is where the spark happens, therefore allowing the igniting of fuel, the width of the gap is determined by the strength of the igniton. The wrong gap on a spark plug can cause your engine to run improperly.  Don’t over tighten when installing the spark plug back into the cylinder head or you’ll be rather annoyed when you want to replace that spark plug and can’t break it loose.  I recommend cleaning the threads on the cylinder head before installing a new plug to rid any dirt that may have collected there.  It’s also a good idea to use a bit of anti-seize on the plug threads, this will eliminate the threads from corroding in the cylinder head. Refer to your service manual for the proper torque on the plug.